Interaction of Three Factors in the Closure of the Ductus Arteriosus

Abstract

Summary

Isolated rings of the ductus arteriosus of the guinea pig developed tension in response to changes in P_O2 and transmural electrical stimulation. Increasing the initial tension potentiated the response to elevated P_O2. In turn, an increase in P_O2 potentiated the responses to transmural stimulation, and also tyramine, norepinephrine and acetylcholine. The three factors, O₂, stretch of the vessel wall and autonomic innervation, may potentiate each other in their vasoactive effect during the initiation of ductal closure, secondary to the respiratory and cardiovascular changes occurring at birth.